/*      $FreeBSD: src/lib/libc/net/getnameinfo.c,v 1.20 2007/02/28 21:18:38 bms Exp $   */
/*      $KAME: getnameinfo.c,v 1.61 2002/06/27 09:25:47 itojun Exp $    */

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * Copyright (c) 2000 Ben Harris.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * Issues to be discussed:
 * - Thread safe-ness must be checked
 * - RFC2553 says that we should raise error on short buffer.  X/Open says
 *   we need to truncate the result.  We obey RFC2553 (and X/Open should be
 *   modified).  ipngwg rough consensus seems to follow RFC2553.
 * - What is "local" in NI_FQDN?
 * - NI_NAMEREQD and NI_NUMERICHOST conflict with each other.
 * - (KAME extension) always attach textual scopeid (fe80::1%lo0), if
 *   sin6_scope_id is filled - standardization status?
 *   XXX breaks backward compat for code that expects no scopeid.
 *   beware on merge.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <netdb.h>
#include <resolv.h>
#include <string.h>
#include <stddef.h>
#include <errno.h>

static int      getnameinfo_inet(const struct sockaddr *, socklen_t, char *,
                                 size_t, char *, size_t, int);
#ifdef INET6
static int      ip6_parsenumeric(const struct sockaddr *, const char *, char *,
                                 size_t, int);
static int      ip6_sa2str(const struct sockaddr_in6 *, char *, size_t, int);
#endif
static int      getnameinfo_link(const struct sockaddr *, socklen_t, char *,
                                 size_t, char *, size_t, int);
static int      hexname(const u_int8_t *, size_t, char *, size_t);

int
getnameinfo(const struct sockaddr * __restrict sa, socklen_t salen,
    char * __restrict host, size_t hostlen, char * __restrict serv,
    size_t servlen, int flags)
{

        switch (sa->sa_family) {
        case AF_INET:
#ifdef INET6
        case AF_INET6:
#endif
                return getnameinfo_inet(sa, salen, host, hostlen, serv,
                    servlen, flags);
        case AF_LINK:
                return getnameinfo_link(sa, salen, host, hostlen, serv,
                    servlen, flags);
        default:
                return EAI_FAMILY;
        }
}

static const struct afd {
        int a_af;
        size_t a_addrlen;
        socklen_t a_socklen;
        int a_off;
} afdl [] = {
#ifdef INET6
        {PF_INET6, sizeof(struct in6_addr), sizeof(struct sockaddr_in6),
                offsetof(struct sockaddr_in6, sin6_addr)},
#endif
        {PF_INET, sizeof(struct in_addr), sizeof(struct sockaddr_in),
                offsetof(struct sockaddr_in, sin_addr)},
        { .a_af = 0 },
};

struct sockinet {
        u_char  si_len;
        u_char  si_family;
        u_short si_port;
};

static int
getnameinfo_inet(const struct sockaddr *sa, socklen_t salen, char *host,
                 size_t hostlen, char *serv, size_t servlen, int flags)
{
        const struct afd *afd;
        struct servent *sp;
        struct hostent *hp;
        u_short port;
        int family, i;
        const char *addr;
        u_int32_t v4a;
        int h_error;
        char numserv[512];
        char numaddr[512];

        if (sa == NULL)
                return EAI_FAIL;

        family = sa->sa_family;
        for (i = 0; afdl[i].a_af; i++)
                if (afdl[i].a_af == family) {
                        afd = &afdl[i];
                        goto found;
                }
        return EAI_FAMILY;

 found:
        if (salen != afd->a_socklen)
                return EAI_FAIL;

        /* network byte order */
        port = ((const struct sockinet *)sa)->si_port;
        addr = (const char *)sa + afd->a_off;

        if (serv == NULL || servlen == 0) {
                /*
                 * do nothing in this case.
                 * in case you are wondering if "&&" is more correct than
                 * "||" here: rfc2553bis-03 says that serv == NULL OR
                 * servlen == 0 means that the caller does not want the result.
                 */
        } else {
                if (flags & NI_NUMERICSERV)
                        sp = NULL;
                else {
                        sp = getservbyport(port,
                                (flags & NI_DGRAM) ? "udp" : "tcp");
                }
                if (sp) {
                        if (strlen(sp->s_name) + 1 > servlen)
                                return EAI_MEMORY;
                        strlcpy(serv, sp->s_name, servlen);
                } else {
                        snprintf(numserv, sizeof(numserv), "%u", ntohs(port));
                        if (strlen(numserv) + 1 > servlen)
                                return EAI_MEMORY;
                        strlcpy(serv, numserv, servlen);
                }
        }

        switch (sa->sa_family) {
        case AF_INET:
                v4a = (u_int32_t)
                    ntohl(((const struct sockaddr_in *)sa)->sin_addr.s_addr);
                if (IN_MULTICAST(v4a) || IN_EXPERIMENTAL(v4a))
                        flags |= NI_NUMERICHOST;
                v4a >>= IN_CLASSA_NSHIFT;
                if (v4a == 0)
                        flags |= NI_NUMERICHOST;
                break;
#ifdef INET6
        case AF_INET6:
            {
                const struct sockaddr_in6 *sin6;
                sin6 = (const struct sockaddr_in6 *)sa;
                switch (sin6->sin6_addr.s6_addr[0]) {
                case 0x00:
                        if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr))
                                ;
                        else if (IN6_IS_ADDR_LOOPBACK(&sin6->sin6_addr))
                                ;
                        else
                                flags |= NI_NUMERICHOST;
                        break;
                default:
                        if (IN6_IS_ADDR_LINKLOCAL(&sin6->sin6_addr)) {
                                flags |= NI_NUMERICHOST;
                        }
                        else if (IN6_IS_ADDR_MULTICAST(&sin6->sin6_addr))
                                flags |= NI_NUMERICHOST;
                        break;
                }
            }
                break;
#endif
        }
        if (host == NULL || hostlen == 0) {
                /*
                 * do nothing in this case.
                 * in case you are wondering if "&&" is more correct than
                 * "||" here: rfc2553bis-03 says that host == NULL or
                 * hostlen == 0 means that the caller does not want the result.
                 */
        } else if (flags & NI_NUMERICHOST) {
                size_t numaddrlen;

                /* NUMERICHOST and NAMEREQD conflicts with each other */
                if (flags & NI_NAMEREQD)
                        return EAI_NONAME;

                switch(afd->a_af) {
#ifdef INET6
                case AF_INET6:
                {
                        int error;

                        if ((error = ip6_parsenumeric(sa, addr, host,
                                                      hostlen, flags)) != 0)
                                return(error);
                        break;
                }
#endif
                default:
                        if (inet_ntop(afd->a_af, addr, numaddr, sizeof(numaddr))
                            == NULL)
                                return EAI_SYSTEM;
                        numaddrlen = strlen(numaddr);
                        if (numaddrlen + 1 > hostlen) /* don't forget terminator */
                                return EAI_MEMORY;
                        strlcpy(host, numaddr, hostlen);
                        break;
                }
        } else {
                hp = getipnodebyaddr(addr, afd->a_addrlen, afd->a_af, &h_error);

                if (hp) {
#if 0
                        /*
                         * commented out, since "for local host" is not
                         * implemented here - see RFC2553 p30
                         */
                        if (flags & NI_NOFQDN) {
                                char *p;
                                p = strchr(hp->h_name, '.');
                                if (p)
                                        *p = '\0';
                        }
#endif
                        if (strlen(hp->h_name) + 1 > hostlen) {
                                freehostent(hp);
                                return EAI_MEMORY;
                        }
                        strlcpy(host, hp->h_name, hostlen);
                        freehostent(hp);
                } else {
                        if (flags & NI_NAMEREQD)
                                return EAI_NONAME;
                        switch(afd->a_af) {
#ifdef INET6
                        case AF_INET6:
                        {
                                int error;

                                if ((error = ip6_parsenumeric(sa, addr, host,
                                                              hostlen,
                                                              flags)) != 0)
                                        return(error);
                                break;
                        }
#endif
                        default:
                                if (inet_ntop(afd->a_af, addr, host,
                                    hostlen) == NULL)
                                        return EAI_SYSTEM;
                                break;
                        }
                }
        }
        return(0);
}

#ifdef INET6
static int
ip6_parsenumeric(const struct sockaddr *sa, const char *addr, char *host,
                 size_t hostlen, int flags)
{
        size_t numaddrlen;
        char numaddr[512];

        if (inet_ntop(AF_INET6, addr, numaddr, sizeof(numaddr)) == NULL)
                return EAI_SYSTEM;

        numaddrlen = strlen(numaddr);
        if (numaddrlen + 1 > hostlen) /* don't forget terminator */
                return EAI_OVERFLOW;
        strlcpy(host, numaddr, hostlen);

        if (((const struct sockaddr_in6 *)sa)->sin6_scope_id) {
                char zonebuf[MAXHOSTNAMELEN];
                int zonelen;

                zonelen = ip6_sa2str(
                    (const struct sockaddr_in6 *)(const void *)sa,
                    zonebuf, sizeof(zonebuf), flags);
                if (zonelen < 0)
                        return EAI_OVERFLOW;
                if (zonelen + 1 + numaddrlen + 1 > hostlen)
                        return EAI_OVERFLOW;

                /* construct <numeric-addr><delim><zoneid> */
                memcpy(host + numaddrlen + 1, zonebuf,
                    (size_t)zonelen);
                host[numaddrlen] = SCOPE_DELIMITER;
                host[numaddrlen + 1 + zonelen] = '\0';
        }

        return 0;
}

/* ARGSUSED */
static int
ip6_sa2str(const struct sockaddr_in6 *sa6, char *buf, size_t bufsiz,
           int flags __unused)
{
        unsigned int ifindex;
        const struct in6_addr *a6;
        int n;

        ifindex = (unsigned int)sa6->sin6_scope_id;
        a6 = &sa6->sin6_addr;

        if ((flags & NI_NUMERICSCOPE) != 0) {
                n = snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id);
                if (n < 0 || n >= bufsiz)
                        return -1;
                else
                        return n;
        }

        /* if_indextoname() does not take buffer size.  not a good api... */
        if ((IN6_IS_ADDR_LINKLOCAL(a6) || IN6_IS_ADDR_MC_LINKLOCAL(a6) ||
             IN6_IS_ADDR_MC_NODELOCAL(a6)) && bufsiz >= IF_NAMESIZE) {
                char *p = if_indextoname(ifindex, buf);
                if (p) {
                        return(strlen(p));
                }
        }

        /* last resort */
        n = snprintf(buf, bufsiz, "%u", sa6->sin6_scope_id);
        if (n < 0 || (size_t)n >= bufsiz)
                return -1;
        else
                return n;
}
#endif /* INET6 */

/*
 * getnameinfo_link():
 * Format a link-layer address into a printable format, paying attention to
 * the interface type.
 */
/* ARGSUSED */
static int
getnameinfo_link(const struct sockaddr *sa, socklen_t salen __unused,
                 char *host, size_t hostlen, char *serv, size_t servlen,
                 int flags __unused)
{
        const struct sockaddr_dl *sdl =
            (const struct sockaddr_dl *)(const void *)sa;
        int n;

        if (serv != NULL && servlen > 0)
                *serv = '\0';

        if (sdl->sdl_nlen == 0 && sdl->sdl_alen == 0 && sdl->sdl_slen == 0) {
                n = snprintf(host, hostlen, "link#%d", sdl->sdl_index);
                if (n > hostlen) {
                        *host = '\0';
                        return EAI_MEMORY;
                }
                return 0;
        }

        switch (sdl->sdl_type) {
        /*
         * The following have zero-length addresses.
         * IFT_GIF      (net/gif/if_gif.c)
         * IFT_LOOP     (net/if_loop.c, net/disc/if_disc.c)
         * IFT_PPP      (net/sppp/if_spppsubr.c)
         * IFT_SLIP     (net/sl/if_sl.c)
         * IFT_STF      (net/stf/if_stf.c)
         * IFT_L2VLAN   (net/vlan/if_vlan.c)
         * IFT_BRIDGE   (net/bridge/if_bridge.c)
         */
        /*
         * The following use IPv4 addresses as link-layer addresses:
         * IFT_OTHER    (net/gre/if_gre.c)
         */
        /* default below is believed correct for all these. */
        case IFT_ARCNET:
        case IFT_ETHER:
        case IFT_FDDI:
        case IFT_HIPPI:
        case IFT_ISO88025:
        default:
                return hexname((u_int8_t *)LLADDR(sdl), (size_t)sdl->sdl_alen,
                    host, hostlen);
        }
}

static int
hexname(const u_int8_t *cp, size_t len, char *host, size_t hostlen)
{
        int i, n;
        char *outp = host;

        *outp = '\0';
        for (i = 0; i < len; i++) {
                n = snprintf(outp, hostlen, "%s%02x",
                    i ? ":" : "", cp[i]);
                if (n < 0 || n >= hostlen) {
                        *host = '\0';
                        return EAI_MEMORY;
                }
                outp += n;
                hostlen -= n;
        }
        return 0;
}